Electrolytic cathode-diaphragm structure



vApril 26, 1932. K. E. STUART ELECPROLYTIC CATHODE DIAPHRAGM STRUCTURE Filed May '7, 1928 5 Sheets-Sheet 1 TEN/ April 26, 1932. K. E. STUART ELECTROLYTIC CATHODE DIAPHRAGM STRUCTURE 5 Sheets-Sheet 2 Filed Ma y 7, 1928 Zlrwentot:

April 26, 1932. p K. E. STUART ELECTROLYTIC CATHODE DIAPHRAGM STRUCTURE Filed May 7, 1928 5 Sheets-Sheet 3 April 26, 1932. K. E. STUART ELECTROLYTIC CATHODE DIAPHRAGM STRUCTURE Filed May '7, 1928 5 Sheets-Sheet 4 M. W M 3 J2 attorney April 26, 1932. K. E. STUART ELEC TROLYTIC CATHODE DIAPHRAGM STRUCTURE Filed May 7, 1928 5 Sheets-Sheet 5 1% M MOW Patented Apr. 26, 1932 UNITED STATES PATENT OFFICE KENNETH E. STUART, F NIAGARA FAL IIS, YORK, ASSIGNOR TO HOOKER-ELECTRO- GHEMICAL'COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK ELECTROLYTIC carnonnnmrimae u STRUCTURE Application filed May 7', was. Serial m. 275,860.

This invention relates to porous diaphragms for electrolytic cells and particularly to diaphragms of fibrous material, and to a method and apparatus for constructing '5 the same. It has for its object the provision of an inexpensive method of applying such diaphragms to perforated cathode plates and particularly when such plates are of irregular, warped or noncylindrical, non-planar form, in such manner that there shall be no joints or seams. in such diaphragms. This object is accomplished by starting with the fibrous raw material, such as asbestos fiber, instead ofusing paper made from the same fiber, as has heretofore been customary, and is carried out by immersing such cathode in a tank filled with pulp formed by maintaining the fibrous material in suspension, preferably in water, and by drawing the water :0 through the perforations, preferably by applying vacu m to the reverse side, and thus depositing the fibers upon the surface so as to form an'unbroken seamless coating of fibrous material of any desired thickness.

The accompanying drawings will serve as an illustration of a method of putting my invention into practice.

Fig. 1 is a plan view of a cathode plate of the character described and provided with ac projecting portionsor fingers. A 0

Fig. 2 is a'sectional end elevation on the line 2-2 of Fig. 1.

Fig. 3 is a sectional elevation of the pulp tank showing the cathode plate in position and the method of maintaining the fiber in suspension.

Fig. 4.- is a part sectional plan View through the pulp tank and the fin ers of the cathode plate, on thg'line of ig. 3.

Fig. 5 is a genef'al view in plan showing the pulp tank with cathode plate in position and the meansfor applying vacuum to it and for removal of the water drawn through the perforations. I

Fig. 6 is a general view in elevation of the same, showing in addition the means for raising and lowering the cathode plate into position in the pulp tank.

Fig. 7 is a general view in elevation of the W same, showing the cathode plate raised for such as 6. i

draining, also in alternative position for inspection and removal.

Fig. 8 is a sectional end elevation of a modi fied form of pulp tank adapted for depositing a diaphragm upon a flat cathode. plate of ordinary form.

Referring to Figs. 1 and 2:

1 is the active perforated surface of the cathode 2 and as shown is formed with a flat portion having hollow rectangular members or fingers 3 projecting at right angles to the fiat surface. Boththe flat surface and the projecting fingers may be formed of perforated sheetmetal, but for reasons that will be stated more fully later, I prefer to use woven wire screen as illustrated in ig. 2. The-active perforated portion of this cathode is supported by a nonperforated back 4 of box section having the flanges 5 adapted to be clamped against the side of the cell body (not shown). .This box section which remains outside thecell serves to receive'the catholyte, such as caustic soda or potash, also the gaseous product formed upon the cathode,

such as hydrogen. The projecting fingers 3 may bereinforced by any suitable structure Referring to Figs. 3, 4, 5, 6, '2" and 8, 7 is the pulp tank above referred to of rectangular form and of such dimensions as to adapt it to receive the cathode 2 with the fingers 3 hang- '80 ing vertically downward and the flanges 5 resting upon the upper edges of the side and end walls, the fingers 3 being preferably symmetrically spaced between said side walls. 8 is a false bottom forming an inverted V, the peak of which is substantially central and the sides of which, form with the side walls of the tank valleys in which may be housed the pipes '9. These are preferably in sections, eight to each side. Each pair of pipes are joined in a common T, each pair of Ts are joined in a common header, each pair of headers are joined to a common feeder, and the two feeders are joined in a common pipe'lO which passes through the side wall of the tank and is controlled by the valve 11. Inthis way all sections of the pipe 9 are served exactly alike. The pipes 9 are perforated in two rows. One row of perforations is preferably directed 100 through the wire screen of the cathode. The tank 13 is connected to the non-perforated back of the cathode through the valve 14,

p'pes and 16, swing joints 17, pipes 18,

swing joints 19 and pipes 20. r

The tank 13 may be put in connection either with a vacuum pump (not shown) through the valve 21 and pipe 22, or with a pressure pump (not shown) through valve 23 and pipe 24. The gauge 25 serves to indicate'the degree of vacuum or pressure applied to the tank 13. The sight glass 26 shows when the water in the tank 13 approaches the top. The pipe 27 is connected to the. tank13 at a predetermined distance above the bottom and is controlled by the valve 28. The pipe 29 is connected to the bottom of the tank 13 and leads thence over the side of the tank 7. It is controlled by the valve 30.

The pipe 18 may be raised and lowered by the chain hoist ,31, pivoting about the swing 'oints 17 Thecathode 2 may be raised and owered b the chain hoist 32, the pipes 20 pivoting a out the swing joints 19.

A pipe 33 is laid along the upper edge of the splash top 34 of the tank 7 and through Ts and headers and the valve 35 is connected'to the pipe 10. The pipe 33 is perforated in a row directed toward the interior of the tank 7.' E.

) The operation of the process is as follows While it is ossible to use air for agitation of the pulp; have found that water is preferable, and that the water which must be supplied tothe tank 7 to replace that drawn through the screen to the tank 13 is sufficient for the purposes of agitation when used in the manner that will now be described. I

A predetermined weight of the dry, fibrous asbestos having been placed'inthe tank 7,

water is introduced through the perforated ipes 9 by openin the valve 11. When the bers are thoroug ly wetted into a pulp the cathode is lowered into position and the water turned on full. When thewater level covers the back of the cathode the vacuum is gradually turned on. Immediately the rise of the waterle'vel is checked and as the-diaphragm begins to build up more vacuum can be turned on untilthe valve 14 is wide open.

After a few minutes the water level be 'ns to rise agam, and this must be checker? by 1 met gradually closing the valve 11. At this stage a part of the water may be supplied through the upper pipe 33. The purpose of this 'will be explained later. After ten or fifteen minutes the process is complete, With the vacuum still on, the cathode is then lifted out of the tank 7 ,bein prevented from touching the sides of'the tan by proper coordination between the lift of the two hoists 31 and'32. When clear of the splash top 34 the cathode is lifted into the position shown in Fig. 7. In this position all the water isdrained out of the cathode. The vacuum is allowed to act upon the diaphragm for several minutes, compacting it and squeezing out the water. After drying, the cathode is detached from the pipes 20 by uncoupling the unions 36, and moved away by the conveyor to be applied to a cell.

The direction of the water jets is such that agitation-rather than circulatlon is produced.

This is important, since circulation would wrap the pulp in thick wads around the edges of the fingers 1. (For this same reason, no form of mechanical agitation is satisfactory.) The erforations are spaced so that the jets are dlrected between the fingers rather'than against them, as shown in Fig. 4.

In fact, they are liable to receive-more than To control-this, the water suptheir share. ply through the pipe 33 is provided. By properly regulating the supply. above and below, a uniform coating can be applied all over the screen. The thickness of the coating is readil controlled by the quantity of fiber weighe into the tank 7.

' The inverted V bottom serves to accumulation of pulp in what woul revent other- .wise be a dead space between the two rows of pipes 9.

During the initial stage of the process, a certain amount of pulp is drawn into the tank 13. This is allowed to settle, and the supernatant water is then discharged through the pipe 27. Finally, the pulp remaining-indigo tank 13 is returned to the tank7 by opening the valve 30 and applying air pressure through the pipe 24.

Iprefer to make the active perforated plate of woven wire screen rather than of perforated sheet metal as the wires give a. better bond for the fibers and, besides, aflord -a greater 'area of active surface, owing to their corrugation and exposed, sides.

dliigrgf fshows ai modified form of tank 7 a a te or app ying diaphragms by this bod to an ordinary flat cathode plate. My inventlon is not limited, however, to

= B as asbestos fiber, is deposited on the active erforated surface of a cathode structure, y bringin a suspension of the fibrous materialin a iquid, such aswater, into contact with the active perforated surface of the cathode, and 'bythe application of difl'erential pressure forcing the liquid of the suspension through the perforations of the active surface; particularly to such a method wherein the fibrous material is maintained in "1 suspension by means of jets of water, said jets being preferablydirected to cause agitation rather than circulation; and particularly also to such a method in which op and bottom jets of water are so balanced as to 2 to gilve a uniform coating of the fibrous materia My invention also comprises suitable for carrying the above -method of making electrolytic cathode-diaa paratus I phragm structures into effect; and the elec-- trolytic cathode-diaphragm structures thus produced. V

I claim 1. A method of making electrolytic cathode-diaphragm structures which comprises bringing a suspension of asbestos in ,Water into contact with the active perforated surface of an electrolytic ,cathode having a warped active surface and forcing the water of the suspension through the perforations of said surface by the application of suction to the interior of said cathode, wherein the asbestos is kept in suspension by means of upwardly directed jets ofwater submerged -in the suspension.

2. A method of making electrolytic cathode-diaphragm structures which comprises bringing a suspension of asbestos in water into contact with the active perforated surface of an" electrolytic cathode having a warped active surface and forcing the water of .the. suspension through the perforations of said surface bythe application of suction to the interior of said cathode, wherein the asbestos is kept in suspension by means of upwardly directed jets of water submerged in the suspension, said jets being disposed to produce agitation of the suspension substantially without circulation thereof.

3. A method of making electrolytic cathode-diaphragm structures which comprises bringing a suspension of asbestos in water into contact with the active erforated surface of an electrolytic cat ode having a .warped active surface and forcing the water of thesuspension through the perforations of said surface b to the interior 0 said cathode, wherein the asbestos is kept in suspension by means of upwardly directed jets of water submerged in 1 the suspension, said jets being ,disposed to produce agitation of the suspension substantially without circulation thereof, and wherein the uniformity of deposit is maintained by downwardly directedjets of water cooperating with said upwardly directed jets to maintain a uniform concentration of asbestos in the suspension. I

4. Apparatus for the production of electrolytic cathode-diaphragm structures comod ascribed prising a container adapted to contain a suspension of asbestos in Water and to support an electrolytic cathode with its'active surfacein contact with said suspension, said container having a bottom shaped to cooperate with perforated pipes, connected to a source of water supply and adjacent to said bottom, to keep the asbestos suspended in the water, and a second container connected with a source of vacuum, and connectible by a conduit with the interior of said cath- 5. Apparatus for the production of electrolytic cathode-diaphragm structures comprising a container adapted to contain a suspension of asbestos in water and to support an electrolytic cathode with its active surface in contact with said suspension, said con-' tainer having a bottom shaped to cooperate with perforated pipes, connected to a source of water supplyand adjacent to said bottom,

to keep the asbestos suspended in the water, and a second container connected with a source of vacuum, connectible by a conduit' w1th the interior of said cathode and connected by a s'econdconduit with the first container above mentioned. 4 p

In testimony whereof, I aflixmy si ature.

KENNETH E. ST ART.

he application of suction. 

